Facebook admits, for the 4th time, that it messed up its measurement metrics

Facebook announced on Friday that it had made another measurement error, this time affecting publishers that use its Instant Articles content platform.

It marks the fourth time in recent months Facebook has acknowledged overstating or understating the metrics that publishers or advertisers use to measure the effectiveness of their activity on the platform.

In the latest disclosure, Facebook said comScore, a third-party measurement firm it partners with, found the social network was undercounting traffic from iPhone users to their Instant Articles content.

Instant Articles is a platform Facebook launched last year in which publishers upload their content directly to Facebook to make it load faster than a standard web page. Publishers can sell their own ads and keep 100% of the proceeds or get Facebook to sell the ad slots for them and allow the social network to take a 30% cut of that revenue.

In all of these cases, none of the errors had any effect on the amount advertisers were charged for Facebook advertising.

Facebook will be hoping that its transparent communication about software bugs and measurement issues will reassure advertisers they can trust the data they are receiving from the social network. But the negative headlines could also raise concerns among advertisers and publishers that the Facebook measurement data they plan their social-media activity around has the potential to be inaccurate.